1. Field of the Invention
The present invention relates to a moving picture data compression device for reading and compressing moving picture data recorded on a recording medium.
2. Description of the Related Art
Along with the diversification of communication equipment in recent years, there have been proposals for various technologies performing communications and the like by using moving picture data after compressing it to reduce the data volume. One example of a moving picture data compression method well known in the art Is the MPEG (Moving Picture Experts Group) method.
Conventional recording media for recording moving picture data include videotapes, laser discs, and the Like. In recent years, such media as a hard disk and a video file (for example, ITU-R656 format video file) have also been used to store moving picture data. The videotape and the laser disc are known an realtime recording media because they can record moving picture data to be read sequentially according to the passage of time. The hard disk and video file are known as non-realtime recording media because they can record moving picture data to be read without concern for the passage of time.
There are two types of MPEG moving picture data compression device: a first type that compresses video data in real time; and a second type (software type) that performs its entire compression operation by executing a software process.
The first type of moving picture data compression device, however, has the capability of compressing only moving picture data read from a realtime recording medium. Accordingly, when a user desires to compress moving picture date from a non-realtime recording medium, he/she has to use the second type of compression device. Thus, according to the kind of data to be compressed, the user has to change the compression device to be used. This in troublesome for the user.
Considering this problem, it is conceivable to use the first type of device also to compress data from non-realtime data recording medium. According to this conceivable method, moving picture data read from a non-realtime recording medium (hereinafter referred to an non-realtime data) is first converted into moving picture data that can be recorded on a realtime recording medium (hereinafter referred to as realtime data). The resultant non-realtime data is then recorded temporarily onto a realtime recording medium such as a videotape. The recorded realtime data is then played beck on a video player or the like and is compressed by the moving picture data compression device of the first type. This method can pave the way for compressing non-realtime data using the moving picture data compression device of the first type. However, it requires a troublesome operation to compress non-realtime data.
It is also conceivable to execute editing processes such as noise elimination and gamma correction on non-realtime data in a manner described below. That is, non-realtime data in first converted to realtime data and then recorded onto a realtime recording medium. Subsequently, an editing device, corresponding to the desired editing process, is connected to the moving picture data compression device. Then, the realtime data is played beak and inputted to the moving picture data compression device. According to this operation, troublesome and complex operation is needed.
Hence, in order to perform several types of editing on non-realtime data, it is necessary not only to perform the above complex operations, but also to prepare individual editing equipment for handling each process.
Further, editing in performed after converting non-realtime data to realtime data. As a result, the same extremely difficult problems associated with processing ordinary realtime data, such as performing time lapse and rewind processes, are present in this case as well.
Even in order to perform relatively simple editing processes such as brightness adjustment, gamma correction, fade in, fade out, and the like, it is still necessary to prepare separate editing devices for each process. As a result, it in still necessary to perform complex operations in order to edit non-realtime data.
In view of the foregoing, it is an object of the present invention to provide an improved moving picture data compression device that is capable of compressing not only moving picture data read from realtime recording media (realtime data), but also moving picture data read from non-realtime recording media (non-realtime data) by a simple operation.
It is another object of the present invention to provide an improved moving picture data compression device that is capable of facilitating the process of editing non-realtime data and of broadening the scope of such editing.
In order to attain the above and other objects, the present invention provides a moving picture data compression device for compressing moving picture data read from a recording medium recorded with moving picture data, comprising: non-realtime data receiving means for receiving moving picture data read from a non-realtime data recording medium, which is recorded with moving picture data that is capable of being read unrelated to the passage of time; synchronization signal generating means for generating a synchronization signal based on moving picture data received by the non-realtime data receiving means; realtime data receiving means for receiving moving picture data that is read from a realtime data recording medium, which is recorded with moving picture data capable of being read sequentially according to the actual passage of time; additional synchronization signal generating means for generating a synchronization signal according to the receiving operation by the reltime data receiving means; and compressing means for selectively executing either non-realtime data compression operations for compressing moving picture data received by the non-realtime data receiving means according to the synchronization signal generated by the synchronization signal generating means or realtime data compression operations for compressing moving picture data received by the realtime data receiving means according to the synchronization signal generated by the additional synchronization signal generating means.
The synchronization signal generating means produces a synchronization signal based on moving picture data (non-realtime data) received from the non-realtime data recording medium. Although this synchronization signal is not always generated at a uniform interval, the compressing means is configured to be capable of executing non-realtime data compression operations onto the non-realtime data, according to the synchronization signal generated by the synchronization signal generating means. For this reason, the moving picture data compression device of the present invention is capable of easily compressing non-realtime data accurately and reliably.
The compressing means is configured to be capable of selectively executing either realtime data compression operations or non-realtime data compression operations. When executing realtime data compression operations, the compressing means can compress moving picture data (realtime data), in accordance with the synchronization signal generated by the additional synchronization signal generating means. When executing non-realtime data compression operations, the compressing means can compress moving picture data (non-realtime data), in accordance with the synchronization signal generated by the synchronization signal generating means. Hence, the Compressing means can easily compress both realtime and non-realtime data. Hence, the present invention can easily compress moving picture data recorded on various types of recording media and can provide this compressed data for various applications such as communications.
The non-realtime data receiving means may include non-realtime data reading means for reading moving picture data from the non-realtime data recording medium, wherein said synchronization signal generating means generates the synchronization signal based on the moving picture data read by the non-realtime data reading means, and wherein said compressing means executes the non-realtime data compression operations for compressing moving picture data, read by the non-realtime data reading means, according to the synchronization signal. The non-realtime data receiving means may further include non-realtime data read controlling means for controlling operations of the non-realtime data reading means to read moving picture data from the non-realtime date recording medium.
The synchronization signal generating means may generate the synchronization signal based on the moving picture data from the non-realtime data recording medium, in accordance with the reading operation achieved by the non-realtime data reading means as controlled by the non-realtime data read controlling means. The realtime data receiving means may include realtime data reading means for reading moving picture data from a realtime data recording medium.
The compression means may include witching means for receiving an instruction signal indicative of a desire whether to perform the realtime data compression operations or to perform the non-realtime data compression operations, and for switching the function of the compressing means between the realtime data compression operations and the non-realtime data compression operations according to the received instruction signal.
According to this structure, the switching means enables the compression means to switch, according to the received instruction signal, between executing realtime data compression operations and executing non-realtime data compression operations. Accordingly, if both realtime data and non-realtime data are inputted simultaneously, the moving picture data compression device can ensure that only a desired type of data will be compressed. Hence, it is possible to reliably compress only the desired data. Further, when both realtime and non-realtime data are inputted simultaneously, it is possible to switch the data to be compressed at desired timings and connect the data together later, enabling a wide variety of editing effects.
The moving picture data compression device may further comprise delaying means for controlling the compressing means to delay performing the non-realtime data compression operations when a time interval, in which the synchronization signal generating means generates a synchronization signal, is longer than a period of time required by the compressing means to perform non-realtime data compression operations.
When the time interval required for the synchronization signal generating means to generate a synchronization signal is longer than the time required for the compressing means to perform a compression operation on non-realtime data, the delaying means delays the non-realtime data compression operation performed by the compression means. As described above, the synchronization signal generated by the synchronization signal generating means is not always a uniform time interval. Therefore, if the interval required to generate the synchronization signal in longer than the time required for the compression means to perform a non-realtime data compression operation, the delaying means controls the compression means to delay in performing the non-realtime data compression operation. Accordingly, it is possible to execute accurately and reliably a non-realtime data compression operation with the compression means.
The compressing means may detect a difference between successively-received moving picture data to execute at least non-realtime data compression operations, wherein the delaying means controls the compression means to delay performing the non-realtime data compression operations by controlling the compressing means to halt temporarily operations at least involved in detecting the difference.
The compressing means may utilize the difference between successively-received sets of moving picture data to execute non-realtime data compression operations. This is a relatively common compression method used, for example, in MPEG format and the like and is very effective for compressing moving picture data. In this case, the delaying means delays the non-realtime data compression operations by temporarily halting operations by the compressing means related to detecting the difference. It is noted that generally, calculation of this difference is performed in a closed loop feedback process regardless of whether the calculation is performed on software or hardware. For this reason, data can gradually change if operations related to detection of the difference calculation are not halted. Further, errors will possibly occur if new moving picture data to be used for calculating the difference is no longer inputted. Accordingly, non-realtime data compression operations are delayed by temporarily halting operations related to the difference calculation. Accordingly, non-realtime data compression operations can be executed even more accurately and reliably. Accordingly, the present invention has the effect of being able to more reliably and accurately execute the compression of non-realtime data.
The moving picture date compression device may further comprises processing means capable of executing at least two types of processes on either one of moving picture data read by the non-realtime data reading means and operations of the non-realtime data reading means; and selecting means for selecting the process to be executed by the processing means.
With the construction described above, the processing means can execute at least two types of processes on the non-realtime data or the operations of the non-realtime date reading means. The selecting means selects a process that the processing means executes on either the moving picture data or the operations. Accordingly the device of the present invention can directly execute the desired processes on the non-realtime data. Moreover, the present invention enables a desired process to be selected and executed from a plurality of processes, without the need to reconnect a corresponding equipment to the device. Accordingly, non-realtime date can be edited with ease.
It is therefore possible to easily perform a wide variety of processes, such as rewind and time elapse processes, on non-realtime data using simple conversion processes performed with computer programs, for example. Operations of the non-realtime data reading means can be processed in a similar manner. Further, when performing processes on non-realtime data or on reading operations using software conversion processes, it is extremely easy to select and execute desired processes from a plurality of available processes merely by switching software programs. Therefore, without complicating the structure of the device, the present invention enables the user to perform a wide variety of processes, thereby increasing the number of editing operations capable of being effected on non-realtime data.
The compressing means may receive either one of the non-realtime data processed by the processing means and the non-realtime data read by the non-realtime data reading means whose operation is processed by the processing means, further comprising delaying means for controlling the compression means to delay performing compression operations when a period of time, required for the processing means to execute selected processes, is longer than another period of time required for the compressing means to perform the non-realtime data compression processes.
Thus, when the time required for the processing means to execute selected processes is longer than the time required for the compressing means to perform a compression operation, the delaying means delays the compression operation. Accordingly, it is possible to execute compression operations accurately and reliably even when a relatively long period of time is required to execute selected process.
For example, the compressing means may compress data using the difference between successively-received sets of moving picture data. If the operations performed by this compression means are quicker than the time interval in which moving picture data is inputted to the compression means, an error will possibly be generated because the data becomes altered or because new moving picture data, required to detect the difference between successive moving picture data, has not been inputted. Therefore, by delaying the compression operation, it is possible to execute compression operations accurately and reliably. Accordingly, the compression operations can be executed accurately and reliably even when the selected process is relatively complex, for example even when the selected process is a process executed in software that has a relatively large number of steps. Therefore, the present invention has the effect of enabling the user to further increase the range of editing operations capable of being effected onto non-realtime data.
The processing means may execute the selected processes on the non-realtime data before the compressing means perform compression operations. When executing processes on non-realtime date before the data is compressed by the compressing means, the process can be executed directly on the original non-realtime data. Therefore, it is possible to perform an extremely wide variety of processes. Accordingly, the present invention has the affect of enabling a greater editing range for non-realtime data.
The processing means may execute the selected processes on non-realtime data after the compressing means performs compression operations onto the non-realtime data. Less data need be processed when processing non-realtime data that has already been compressed by the compressing means into variable-length encoded data, for example. Accordingly, processing is simplified and can be performed faster. Accordingly, the present invention further reduces the time required to edit non-realtime data. In addition, less memory capacity is required to store the reduced amount of data, thereby reducing production costs.
The non-realtime data may include indication data indicating processes to be executed by the processing means wherein the selecting means selects the processes indicated by the indication data. When non-realtime data includes indication data indicating processes to be executed by the processing means, the selecting means automatically changes the processes to be selected based on the indication data. Hence, simply by assigning indication data to non-realtime data, it is possible to automatically let the processing means perform a desired editing operation on non-realtime data. Accordingly, the present invention further simplifies the editing of non-realtime data.
According to another aspect, the present invention provides a moving picture data compression device for compressing moving picture data read from a recording medium recorded with moving picture data, comprising: non-realtime data receiving means for receiving moving picture data from a non-realtime data medium that is recorded with moving picture data capable of being read without regard for the passage of time; compressing means capable of compressing moving picture data; processing means capable of executing at least two types of processes on moving picture data received by the non-realtime data receiving means; and selecting means for selecting the process for the processing means to execute on the moving picture data.
The non-realtime data receiving means may includes: non-realtime data reading means for reading moving picture data from the non-realtime data medium; and read controlling means for controlling the operations of the non-realtime data reading means, wherein the processing means is capable of executing at least two types of processes on either moving picture data read by the non-realtime data reading means or operations of the non-realtime data reading means that are controlled by the read controlling means, the selecting means selecting the process for the processing means to execute on the moving picture data or the operations.
According to still another aspect, the present invention provides a moving picture data compression device for compressing moving picture data read from a recording medium recorded with moving picture data, comprising: a non-realtime data receiving unit receiving moving picture data read from a non-realtime data recording medium, which is recorded with moving picture data that is capable of being read unrelated to the passage of time; a synchronization signal generating unit generating a synchronization signal based on moving picture data received by the non-realtime data receiving unit; a realtime data receiving unit receiving moving picture data that is read from a realtime data recording medium, which in recorded with moving picture data capable of being read sequentially according to the actual passage of time; an additional synchronization signal generating unit generating a synchronization signal according to the receiving operation by the realtime data receiving units and a compressing unit selectively executing either non-realtime data compression operations for compressing moving picture data received by the non-realtime data receiving unit according to the synchronization signal generated by the synchronization signal generating unit or realtime data compression operations for compressing moving picture data received by the realtime data receiving unit according to the synchronization signal generated by the additional synchronization signal generating unit.
According to a further aspect, the present invention provides a moving picture data compression device for compressing moving picture data read from a recording medium recorded with moving picture data, comprising: a non-realtime data receiving unit receiving moving picture data from a non-realtime data medium that is recorded with moving picture data capable of being read without regard for the passage of time; a compressing unit capable of compressing moving picture data; a processing unit capable of executing at least two types of processes on moving picture data received by the non-realtime data receiving unit; and a selecting unit selecting the process for the processing unit to execute on the moving picture data.